The objective of this project is to determine if there is a defect in axonal or dendritic flow of particulate matter in cortical neurons of patients suffering from senile dementia/Alzheimer's Disease. To this end, neurons in experimental animals and in man will be studied in-vitro to determine normal patterns of anterograde and retrograde particulate neuroplasmic flow. Movements will be observed visually and by means of time-lapse motion pictures using Nomarski optics on living cultures in a tissue culture chamber. In addition, the effects on such particulate movements by alterations in oxygen concentration, temperature, and the presence in the medium of small concentrations of mitotic spindle inhibitors will be studied.